U.S. Amps US-1800 User manual

Brand: U.S. Amps

Model: US-1800

Category: Supplementary music equipment

Type: User manual

B-52 US Series Professional Power Amplifiers - Instruction Manual

THE BEAUTY OF POWER

US SERIES AMPLIFIERS

OWNERS MANUAL

US-SERIES

PROFESSIONAL POWER AMPLIFIERS

US-1200

US-1800

US-3000

US-4000

THE BEAUTY OF POWER

B-52 US Series Professional Power Amplifiers - Instruction Manual

US SERIES AMPLIFIERS

CONTENTS

Introduction ................................................... 3

Warnings and Safety Instructions ..................... 4-5

Features ........................................................ 5

Power Ratings at a Glance .............................. 6

US-Series Features .......................................... 7

Front Panel Controls ....................................... 8-9

Rear Panel Controls ........................................ 10-13

Protection ..................................................... 13-15

Setup ............................................................ 15-16

Connections ................................................. 17-18

Wiring ......................................................... 19

Speciﬁcations ................................................ 20

Warranty ...................................................... 21

Notes ........................................................... 22-23

Contact Information ........................................ 24

B-52 US Series Professional Power Amplifiers - Instruction Manual

THE BEAUTY OF POWER

US SERIES AMPLIFIERS

WELCOME TO THE B-52 FAMILY

Thank you for purchasing a US-Series Professional Power Ampliﬁer.

At B-52, we believe in over-

building all of our products and the US-Series Professional Power Ampliﬁers are no exception. We took our time in de-

signing these stellar looking amps to outperform the competition on any stage, in the clubs and on the road. To achieve

studio quality audio reproduction we utilized low noise, low distortion circuitry and high current output stages.

We used oversized toroidial transformers and large ﬁlter capacitors to deliver super clean, ﬁst pumping output even

when driving a 2 ohm speaker load. These ampliﬁers use the most reliable linear output devices which provide ultra low

distortion and a ruler ﬂat frequency response. The US-Series is backed by our rock solid 3-year warranty and our com-

mitment to reliability known the world over.

It is imperative that you read and understand all of the warnings in this manual regarding proper usage, service

and safety. Failing to comply with any of these safety and operation warnings may void your warranty.

For more information about your US Series Ampliﬁer, log on to: http://www.B-52Pro.com or call our customer

service support hotline (toll free) at 800-344-4384 or (+1) 323-277-4100.

Thank you again for choosing a US-Series Professional Power Ampliﬁer.

Unpacking and Installation

Your US-Series Ampliﬁer is neither complicated to install nor difﬁcult to operate but you must take some time to

read this manual to ensure a properly wired installation. You will also need to become familiar with the ampliﬁer’s

features and how to use it correctly. Please take care unpacking your ampliﬁer; do not throw away the carton

and other packing materials. The original box may be needed to move your ampliﬁer and will be required if it

becomes necessary to return the ampliﬁer for service. Never place the ampliﬁer near a radiator, in front of heat-

ing vents, direct sun light, excessive humid, dusty locations or near water. Connect your ampliﬁer using the system

components described in this manual.

THE BEAUTY OF POWER

B-52 US Series Professional Power Amplifiers - Instruction Manual

US SERIES AMPLIFIERS

IMPORTANT INFORMATION

Please keep this instruction manual for future reference and for the duration of owning your

US-Series Professional Power Ampliﬁer(s). Please carefully read and comprehend the instructions

inside this manual before attempting to operate the ampliﬁer.

This instruction manual includes essential safety information regarding the use and maintenance

of the US-Series Ampliﬁer. Take special care to heed all warning symbols and signs inside this

manual and those printed on the unit itself.

WARNING

TO PREVENT FIRE OR SHOCK

HAZARD, DO NOT EXPOSE

THE AMPLIFIER TO

WATER OR MOISTURE. DO

NOT OPERATE NEAR ANY

WATER SOURCE

WHAT’S THE MEANING OF THIS?

e lightning ash with an arrow triangu-

lar symbol is intended to alert the user to

the presence of non-insulated “dangerous

oltage” within the product’s enclosure,

and may be of sucient magnitude to

constitute a risk of electric shock

1) Read these instructions.

2) Follow all instructions.

3) Keep these instructions.

4) Heed all warnings.

5) DO NOT turn on the ampliﬁer before connecting all

other external devices.

6) Do not use the ampliﬁer near water. Be extra cautious

when moving the ampliﬁer during rain or while

transporting it over wet surfaces as water might splash

onto the unit.

7) Clean only with dry cloth.

8) Do not block any ventilation openings and operate in

accordance with manufacturer’s instructions.

9) Do not install near heat sources such as radiators,

stoves or other devices that may produce heat.

10) Do not defeat the safety purpose of the polarization or

grounding-type plug. A polarized plug has two blades

with one wider than the other. A grounding-type plug

has two blades and a third grounding prong. The wide

blade or the third prong is provided for your safety. If

the provided plug does not ﬁt your outlet, consult an

electrician for replacement of the obsolete outlet.

11) Protect the power cord from being walked on or

pinched, particularly at the plug and the point where it

exits the ampliﬁer.

WHAT’S THE MEANING OF THIS?

e exclamation point triangular symbol

is intended to alert the user to the presence

of important operating and maintenance

(servicing) instructions in the user manual

accompanying the Amplier.

12) Only use attachments / accessories speciﬁed by

B-52 Professional.

13) Unplug the ampliﬁer during lightning storms and

when not in use.

14) Refer all servicing to qualiﬁed personnel. Servicing

may be required when the unit has been damaged

in any way such as when the power cord or plug is

damaged, liquid has spilled into the unit, the

unit has been exposed to moisture or rain, does not

operate normally, or has been dropped.

15) To reduce the risk of ﬁre or electric shock, do not

expose the ampliﬁer to rain or moisture.

16) Moisture can damage the ampliﬁer and can cause

corrosion of electrical contacts.

17) Keep the unit out of extended or intense direct sun

light. No containers ﬁlled with any type of liquid

should be placed on or near the ampliﬁer.

WARNING

Handle the power

supply cord with care.

Do not damage or

deform it as it may

cause electric shock or

malfunction when used.

Hold the plug attach-

ment when removing

from wall outlet. Do not

pull on the power cord.

B-52 US Series Professional Power Amplifiers - Instruction Manual

THE BEAUTY OF POWER

US SERIES AMPLIFIERS

1. READ INSTRUCTIONS – All the safety and

operating instructions should be read before this

product is operated.

2. RETAIN INSTRUCTIONS – The safety and

operating instructions should be retained for future

reference.

3. HEED WARNINGS – All warnings on the

ampliﬁer and in the operating instructions should

be adhered to.

4. FOLLOW INSTRUCTIONS – All operating and

use instructions should be followed.

5. WATER AND MOISTURE –

The ampliﬁer should

not be used near water - for example, a bathtub,

washbowl, kitchen sink, laundry tub, wet basement, or

near a swimming pool, and the like.

6. CARTS AND STANDS – The ampliﬁer should

be moved with a sturdy cart. An ampliﬁer and cart

combination should be moved

with care. Quick stops, excessive

force, and uneven surfaces may

cause the ampliﬁer and cart

combination to overturn.

7. INSTALLATION – Install in accordance with the

manufacturer’s instructions and local codes.

8. HEAT – The ampliﬁer should be situated away

from heat sources such as radiators, heat registers,

stoves, or other appliances that produce heat.

9. POWER SOURCES – This product should be

operated only from the type of power source indicated

on the rating label. If you are not sure of the type

of power supply to your home, consult your product

dealer or local power company.

10. GROUNDING OR POLARIZATION – This

product may be equipped with a polarized alternation-

current line plug (a plug having one blade wider than

the other). This plug will ﬁt into the power outlet only

one way. This is a safety feature. If you are unable to

insert the plug fully into the outlet, try reversing the

plug. If the plug should still fail to ﬁt, contact your

electrician to replace your obsolete outlet. Do not

defeat the safety purpose of the polarized plug.

11. POWER CORD PROTECTION – Power-supply

cords should be routed so that they are not likely to be

walked on or pinched by items placed upon or against

them, paying particular attention to the cord in cor-

respondence of plugs, convenience receptacles, and the

point where they exit from the ampliﬁer.

12. CLEANING – The ampliﬁer should be cleaned

only as recommended by the manufacturer. Clean by

wiping with a cloth slightly damp with water. Avoid

getting water inside the ampliﬁer.

13. NON-USE PERIODS – The power cord of the

ampliﬁer should be unplugged from the outlet when

left unused for a long period of time.

14. OBJECT AND LIQUID ENTRY – Care should

be taken so that objects do not fall and liquids are not

spilled into the ampliﬁer through openings.

15. DAMAGE REQUIRING SERVICE – The

ampliﬁer should be serviced by qualiﬁed service

personnel when:

A. The power-supply cord or the plug has been

damaged; or

B. Objects have fallen, or liquid has been spilled

into the ampliﬁer; or

C. The ampliﬁer has been exposed to rain; or

D. The ampliﬁer does not appear to operate

normally or exhibits a marked change in

performance; or

E. The ampliﬁer has been dropped, or the chassis

damaged.

16. SERVICING – The user should not attempt any

service to the ampliﬁer beyond that described in the

operating instructions. All other servicing should be

referred to qualiﬁed service personnel.

17. VENTILATION – Slots and openings in the

ampliﬁer are provided for ventilation and to ensure

reliable operation of the product and to protect it from

overheating, and these openings must not be blocked

or covered. The openings should never be blocked

by placing the product on a bed, sofa, rug, or other

similar surface. This product should not be placed in a

built-in installation such as a bookcase or rack unless

proper ventilation as per the manufacturer’s instruc-

tions have been adhered to.

18. GROUNDING – Always maintain reliable

grounding of the rack and all equipment installed in

the rack.

19. POWER – The power switch in your ampliﬁer is

not all-pole AC switch. You must physically disconnect

AC power cord from either ampliﬁer or AC outlet to

fully disconnect it from AC mains. Make sure you have

access to the power cord if you need to disconnect it in

case of emergency.

20. LIGHTNING – For added protection for this

product during a lightning storm, or when it is left

unattended and unused for long periods of time unplug

it from the wall outlet. This will prevent damage to the

product due to lightning and power-line surges.

21. REPLACEMENT PARTS – When replacement

parts are required, be sure the service technician has

used replacement parts speciﬁed by the manufacturer

or have the same characteristics as the original part.

Unauthorized substitutions may result in ﬁre, electric

shock, or other hazards.

22. SAFETY CHECK – Upon completion of any

service or repairs to this product, ask the service

technician to perform safety checks to determine that

the product is in proper operating condition.

IMPORTANT SAFETY PRECAUTIONS

CAUTION: To reduce the risk of electric shock, do not

remove any cover. No user-serviceable parts inside. Refer

servicing to qualiﬁed service personnel only.

The lightning ﬂash with arrowhead symbol within the equilateral triangle is intended to alert the use to the

presence of un-insulated “dangerous voltage” within the product’s enclosure that may be of sufﬁcient

magnitude to constitute a risk of electric shock.

The exclamation point within the equilateral triangle is intended to alert the user to the presence of important

operation and maintenance (servicing) instructions in the literature accompanying this appliance.

To prevent electric shock, do not use a polarized plug with an extension cord, receptacle or other outlet unless the blades

can be fully inserted to prevent blade exposure.

CAUTION

THE BEAUTY OF POWER

B-52 US Series Professional Power Amplifiers - Instruction Manual

US SERIES AMPLIFIERS

POWER RATINGS AT A GLANCE

US-1200 US-1800 US-3000 US-4000

Rated Output Power STEREO BOTH CHANNEL DRIVEN

8 Ohms 210 watts 300 watts 500 watts 700 watts

4 Ohms 330 watts 475 watts 800 watts 1100 watts

2 Ohms 430 watts 700 watts 1200 watts 1600 watts

Rated Output Power BRIDGED MONO

8 Ohms 650 watts 950 watts 1600 watts 2200 watts

4 Ohms 850 watts 1400 watts 2400 watts 3200 watts

Both channels driven @ 1kHz, 1%THD

B-52 US Series Professional Power Amplifiers - Instruction Manual

THE BEAUTY OF POWER

US SERIES AMPLIFIERS

AMPLIFIER FEATURES

The US-Series features four professional heavy-duty power ampliﬁers, covering a wide range of

output power ratings. The models are US-1200, US-1800, US-3000 and US-4000. US-Series

ampliﬁers are built on a rugged, heavy gauge steel chassis with a sturdy aluminum front panel.

The ampliﬁers use advanced circuitry and a well-designed PCB layout to ensure quality sound

and enhanced reliability. Large aluminum heatsinks and an oversized toroidal transformer, com-

bined with comprehensive protection circuitry and variable speed fan(s) provide worry-free and

reliable operation in the most demanding environments.

• Compactsize-upto3200wattsintworackspaces

• Ruggedheavygaugesteelenclosurewithsturdyaluminumfrontpanelforstability

and increased longevity

• High-currenttoroidaltransformersforincreased2-ohmpoweroutput

• 21-positiongaincontrolknobsforconsistentsettings

• SelectableSTEREO,PARALLELMONOandBRIDGEDMONOmodesforexibility

• FrontpanelLEDdisplay:POWER,BRIDGEandPARALLELLEDsandSIGNAL,-20dB,-10dB,

 0dB,CLIPandPROTECTLEDsforeachchannel

• Protection:Shortcircuit,outputcurrentlimiting,thermal,DCoffset,turnon/offmuting,

RF protection and circuit breaker

• Cliplimiterstoreducedistortionwithoutsacricingpeakperformance(defeatableon

 US-3000/US-4000)

• Sub-soniclterstoprotectspeakersandincreaseheadroom(defeatable)

• BalancedcomboXLRand1/4”TRSinputconnectorsandlinkXLRoutputconnectors

• BothbindingpostsandSpeakon™outputconnectors

• Low-noisecoolingfanswithcontinuousvariablespeedandhighlyefcientfront-to-rear

forced air cooling design

• Replaceableopencellfoamairlters

THE BEAUTY OF POWER

B-52 US Series Professional Power Amplifiers - Instruction Manual

US SERIES AMPLIFIERS

FRONT PANEL CONTROLS

2 2

Opposite page

1. RACK MOUNTING POINTS

Points to bolt your ampliﬁer into a rack.

2. AIR VENTS

US-Series ampliﬁers are cooled by two rear-mounted

fans (US-1200 has one fan) and open cell foam ﬁlters

mounted behind the front vents.

CAUTION: Never block the front or rear vents

and keep them clean at all times.

NOTE: Periodically clean the foam ﬁlters using a

vacuum cleaner to avoid dust from blocking the

vents. If the ﬁlters become too dusty, it may

decrease your ampliﬁer’s ability to dissipate

and remove heat efﬁciently. If the ﬁlters become

 toodustyandtoodifculttocleanexternally,you

can access the ﬁlters and remove them for

cleaning. Refer to the cleaning procedure later

in this manual.

3. BLUE ILLUMINATED STRIPS

These two blue illuminated strips glow when your

amplieristurnedON.

4. CHANNEL 1 AND CHANNEL 2

LEVEL CONTROLS

Use these 21-position detented controls to adjust the

output levels of Channel 1 and Channel 2. When

theLEVELcontrolsaresetfullycounter-clockwise,the

signal is attenuated by more than 80dB (marked -∞).

WhentheLEVELcontrolsaresetfullyclockwise,the

signalisampliedwithmaximumgain.Whenthe

LEVELissetfullyclockwise,theamplierproduces

itsratedoutputpowerata4Ohmloadwith+4dBu

(1.23Vrms)signalappliedtotheinputs.Alldetents

are marked in dBs showing the attenuation of

the output signal with reference to the fully

clockwise position.

NOTE:InPARALLELMONOmode,bothofthe

 Channel1andChannel2LEVELcontrolsare

used to adjust the signal level for their respective

channels. The signal should be routed only to

the Channel 1 input in this mode.

NOTE:InBRIDGEDMONOmode,onlythe

 Channel1LEVELcontrolisusedtoadjustthe

signal level. The signal should be routed only to

Channel 1’s input in this mode.

5. SIGNAL Indicators

ThesegreenLEDswillilluminateindicatingthata

signal is being received through the input and that

thesignalisbeingamplied.TherearethreeLEDson

eachchannel:SIGNAL,-20dBand-10dB.

6. CLIP Indicators

TheseredLEDswillilluminateattheclipping

threshold.IftheCLIPLEDslightfrequently,youare

overloading the ampliﬁer, causing gross distortions

on the outputs. Heavy clipping is bad for both your

speakers and ampliﬁers and should be avoided.

B-52 US Series Professional Power Amplifiers - Instruction Manual

THE BEAUTY OF POWER

US SERIES AMPLIFIERS

Reduce the output volume using the speciﬁc channel’s

level controls until the clipping disappears or until the

CLIPLEDsashonlyoccasionally.

7. PROTECT INDICATORS

TheseyellowLEDsindicatethatthechannelisineither

PROTECTmodeorMUTEmode.Whenthechannel

goesintoprotectmodeitsoutputwillturnOFF.Thisis

to protect the speakers connected to that channel.

NOTE:TheprotectLEDwilllightwhenthe

 heatsinkisoverheating.Oncetheaffected

channel’s heatsink cools down, the output signal

 willautomaticallyresumeandthePROTECTLED

 willturnOFF.Constanttriggeringofthethermal

protection indicates blocked vents, dusty air

ﬁlters, possible low load condition, or problems

with your speakers or cables.

NOTE: ThePROTECTLEDswillilluminatefor

about two to three seconds when the ampliﬁer is

 poweredONandtheywillfadeslowlywhenthe

 amplierispoweredOFF.Thisindicatesyour

ampliﬁer is going through a transition process

and the outputs are muted.

WARNING:IfthePROTECTLEDsilluminate

 constantlyanddon’tturnOFF,evenwhen

the speakers are physically disconnected from

the ampliﬁer’s outputs, this indicates a fault.

 ImmediatelyturntheamplierOFF,disconnect

 thepowercordfromtheACoutlet,andreferthe

 ampliertoservicepersonnel.AuthorizedB-52

service centers are listed at www.B-52Pro.com

8. BRIDGE LED

ThisgreenLEDilluminateswhentheMODEswitchon

therearpanelissetintheBRIDGEposition.Usethe

Channel1LEVELcontroltoadjusttheoutputvolume

inBRIDGEMONOmode;theChannel2LEVELcon-

trol is inactive in this mode.

9. POWER LED

TheblueLEDwillilluminatewhenyouramplieris

turnedON.

10. PARALLEL LED

ThisgreenLEDillumiateswhentheMODEswitchon

therearpanelissettoPARALLEL.UsetheChannel1

LEVELcontroltoadjusttheoutputvolumeofChannel

1andtheChannel2LEVELcontroltoadjusttheout-

put volume of Channel 2, even though both channels

amplify the same signal connected to the Channel 1

input.

11. AC POWER SWITCH

UsethisswitchtoturnyouramplierONorOFF.

THE BEAUTY OF POWER

B-52 US Series Professional Power Amplifiers - Instruction Manual

US SERIES AMPLIFIERS

1. FAN(S)

Coolingfanswithvariablespeedcontrols.Airenters

the ampliﬁer through vents located on the front alu-

minium panel. Do not block the front vents or the fans

on the rear panel of the ampliﬁer.

2. INPUT CONNECTORS

Connect the input source to these electronically bal-

ancedComboconnectorsusingeitherXLRor1/4”

TRSplugs.The1/4”TRSandXLRplugarecong-

ured:Pin2(Tip)-hot,Pin3(Ring)-cold,andPin1

(Sleeve)–shield/ground.Werecommendusingbal-

ancedthree-conductorcables.Astereosignalshould

be connected to both the Channel 1 and Channel 2

input jacks for 2-channel (stereo) operation.

NOTE: Unbalancedtwo-conductor1/4”plugs

can also be inserted into these input Combo

connectors. But using unbalanced connectors

may increase noise and hum. See more

information about balanced and unbalanced

 connectionsintheCONNECTIONSsectionlater

in this manual.

NOTE:ForBRIDGEDMONOorPARALLEL

 MONOusetheChannel1inputjackonly.

3. LINK CONNECTORS

TheseXLRjacksareusedtosendasignaltoaseper-

ateamplier(chaining).TheLINKXLRjacksarecon-

nected in parallel to the input Combo jacks.

4. HPF (HIGH PASS FILTER) SWITCH

Use these slide switches to activate the built-in High

Pass ﬁlters. The HPF rolls off signals below 50Hz. This

improves the bass performance of most full range

speakersbyreducinguncontrolledandexcessive

speakerconemotion.EngagingtheHPFswitchwhen

using full range speakers makes more power avail-

able to the speaker’s rated frequency range, leading

to higher SPLs.

REAR PANEL CONTROLS

45 5

B-52 US Series Professional Power Amplifiers - Instruction Manual

THE BEAUTY OF POWER

US SERIES AMPLIFIERS

5. LIMITER switch (US-3000 and

US-4000 models only)

When the sound source signal is too high, the out-

put signal will distort. To prevent this, both channels

feature clip limiters to prevent gross distortions on the

outputs. It is recommended to avoid clipping but if

it does occur, the clip limiters will greatly reduce the

amount of distortion and stress on your speakers and

ampliﬁer. It is recommended to keep these switches in

theONpositionasthiswillresultinbettersoundand

increase the life of your loudspeakers.

NOTE: The US-1200 and US-1800 ampliﬁers

have built-in limiters that are permanently

engaged for constant protection and optimal

performance.

6. BRIDGE / STEREO / PARALLEL SWITCH

Use this switch to change the ampliﬁer’s operating

modetoSTEREO,BRIDGEDMONOorPARALLEL

MONO.SetthisswitchtotheSTEREOpositionfor

normal stereo, or 2-channel operation.

WhensettoPARALLEL,theinputsignalconnectedto

channel1isroutedtobothchannels.ThePARALLEL

MONOmodeisconvenientwhenrunningalong

mono signal cable to a remote power ampliﬁer(s),

and then connecting speakers to both of the channels

inordertoreproducethesamesignal.InPARALLEL

mode the input of channel 2 is inactive and should

not be used in this conﬁguration.

IntheBRIDGEDposition,themonoinputsignalcon-

nected to channel 1 is routed to both the right and

left ampliﬁer channels, yet in this mode the speaker is

connected between the two channels’ hot outputs and

is not referenced to the ground. In this mode the chan-

nel 2 input is inactive.

NOTE:SeetheCONNECTIONSsectionlaterin

 thismanualformoredetailsonPARALLEL

 MONOandBRIDGEDMONOmodes.

WARNING:DONOTswitchtoPARALLEL

 MONOorBRIDGEDMONOunlessyouhave

read and understood these connections and their

limitations as described later in this manual.

7. BINDING POST OUTPUTS

Use the binding posts to connect your loudspeakers

to the ampliﬁer. Binding posts are a good option for

xedinstallationsorwhenyoudonothaveSpeakon-

ﬁtted speaker cables. The high-quality insulated

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binding posts offer a variety of connection options.

Use speaker wires with stripped ends (do not strip

themmorethan½”or12.5mm),usingtheholeson

thebottomofthebindingposts.Ensurethatnopartof

thespeakerwireisexposedwhenconnectedtothe

bindingposts.Alternatively,youcanalsousespeaker

cablesterminatedwithstandardbananaplugs.Make

sure that no part of speaker wire or banana plugs are

exposedwhenconnectedtothebindingposts.

NOTE: US-Series ampliﬁers conﬁgured for use

 inEuropeareprovidedwithpermanentplastic

inserts which prevent using banana plugs for

speaker connection. This is a safety measure

 requiredbyEuropeansafetylaws.

NOTE:IntheBRIDGEDmode,theloudspeaker

must be connected using the two red binding

 posts.Thepositive(+)wirefromtheloudspeaker

must be connected to the Channel 1 red post,

and negative (-) wire from the loudspeaker must

be connected to the Channel 2 red post, as

indicated on the rear panel just below the

binding posts.

WARNING:NEVERCONNECTspeakerswith

an impedance lower than the rated minimum

impedance of the ampliﬁer. The lowest

 impedanceinSTEREOandPARALLELmodesis

 2Ohmsforeachchannel.Thelowestimpedance

 inBRIDGEDmodeis4Ohms.NEVER

 CONNECT2Ohmsratedloudspeaker(s)or

a combination of speakers to the ampliﬁer in the

 BRIDGEDmode.

NOTE:RefertotheCONNECTIONSsection

later in this manual for speaker wire connection

diagrams.

8. SPEAKON™ OUTPUT CONNECTORS

Use these speaker outputs to connect cables ﬁtted with

Speakon™cableconnectors.US-Seriesampliers

have two connectors, one for each channel, to con-

nectSpeakon™ttedcables.The1-pinisconnected

totheground.The1+pinisconnectedtotheoutput

of each channel, which is an industry standard.

You can connect both channel 1 and channel

2 loudspeakers to the Channel 1 output connector.

To do this a quad speaker cable must be used. The

Channel 1 speaker should be connected to pins

1-/1+andtheChannel2loudspeakerisconnectedto

pins2-/2+.

You can use the Channel 1 output connector for

BRIDGEconnectionofyourloudspeakers(whenthe

amplierisinBRIDGEmode).Inthiscongurationthe

loudspeakersconnectedmustusethe2+pinofthe

connector for the loudspeaker’s ground connection

(NOTCONNECTEDTOTHEGROUNDOFAMPLI-

FIER)andpin1+forthespeaker’sHOTconnection.

REAR PANEL CONTROLS (cont.)

45 5

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NOTE:Matchthepindesignationsprintednext

to the output connectors on rear panel to ensure

proper connections.

9. CIRCUIT BREAKER

The circuit breaker protects the ampliﬁer from faults

attheACsupplyandservesasprotectionwhenthe

ampliﬁer fails.

 Ifthecircuitbreakertrips,cuttingACpower

supply to your ampliﬁer, it may indicate a serious

malfunction or failure. Wait for the circuit breaker to

cool before resetting it by simply pressing the reset

knob. If the circuit breaker repeatedly trips, especially

when there is no signal on the inputs or outputs, this

indicatesafailureofyouramplier.DISCONNECT

the power cord from the ampliﬁer immediately and

contact an authorized B-52 Service Center.

There are rare instances when the circuit breaker acts

on a constant heavy overload with a very low imped-

ance load connected to ampliﬁer, protecting your

ampliﬁer against such improper usage. In such cases

you need to check and correct your load (loudspeak-

ers) to provide for the proper load impedance,

and/orreduceoutputsignal.

10. AC INPUT

IECconnectorfortheACpowercable.Connectthe

suppliedheavy-gauge3-pinIECpowercable.

NOTE:NeverdisconnecttheEARTHpinfromthe

 ACconnection.Itwilldefeatsafetymeasures

used in your power ampliﬁer and void the

warranty.

US-Series ampliﬁers feature comprehensive protection

circuitry that protects both the loudspeakers and the

electronics from malfunctioning. The protection is non-

intrusive, sonically transparent and does not affect the

soundunlessthereareextremeconditionsthatacti-

vate the protection circuitry.

ThePROTECTLEDsonthefrontpanelilluminatewhen

the protection is active during the power-up sequence,

when thermal protection is activated, or when there is

amalfunction.WhenthePROTECTLEDsareON,the

ampliﬁer’s outputs are muted.

INITIAL POWER-UP: The protection circuitry will

activate for about two to three seconds from the time

youturnONtheamplier.Thespeakeroutputsare

muted during this period. If the ampliﬁer is operating

normally, the protection circuitry will deactivate and

the ampliﬁer will switch to operation mode.

NOTE:ItisnormalforthePROTECTLEDtofade

 graduallyaftertheamplieristurnedOFF.

THERMAL PROTECTION:Excessiveheat-sinktem-

peratures will engage the thermal protection circuitry

to avoid damage to your ampliﬁer. The speaker

outputwillmuteandthePROTECTLEDwillilluminate.

Thermal protection only engages on the channel

whichhastheoverheatingheatsink,excepttheUS-

1200 where both channels will be muted. The thermal

protection will automatically restore to normal opera-

tion mode automatically once the heatsink tempera-

ture drops to a safe level.

NOTE: If the thermal protection constantly

activates, check the impedance of your loud-

speakers and the condition of the air ﬁlters on

front of the ampliﬁer. The loudspeakers

impedance must not be lower than what is

speciﬁed in this manual for 2-channel and

 BRIDGEoperation.8Ohmsand4Ohmsspeaker

 loadsperchannel(8Ohmsand16Ohmsin

 BRIDGEmode)shouldnottriggerthethermal

protection circuitry if the air access is not

 blockedandtheairltersareclean.2Ohms

 speakerloadsperchannel(4OhmsinBRIDGE

mode) can cause the thermal protection circuitry

to activate occasionally. If this occurs, decrease

the signal level and consider reconthe speakers

connections to reduce the load on the ampliﬁer

 (forexample,donotconnecttoomanyspeakers

in parallel to the same channel).

NOTE:Makesurethereisadequateairaccess

PROTECTION

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B-52 US Series Professional Power Amplifiers - Instruction Manual

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to the ampliﬁer. Do not block the air vents on

the front and do not block the fans on the rear

 panel.Makesuretheopencellfoamairlters

behind the vents on the front of the ampliﬁer are

clean. If necessary, use a vacuum cleaner to

clean these air ﬁlters.

NOTE: If the air ﬁlter become too dirty, the

ampliﬁer may not operate normally as air

circulating inside the ampliﬁer may become too

hot, thereby triggering the thermal protection.

If you cannot properly clean the air ﬁlters

 externallywithavacuum,removetheairlters

from the ampliﬁer and clean them thoroughly.

 ThisprocedureSHOULDbeperformedBYA

 QUALIFIEDPERSONNELONLY!Disconnectyour

ampliﬁer completely from its power source –

 YOUMUSTPHYSICALLYDISCONNECTTHE

 POWERCORDANDNOTJUSTTURNOFFTHE

 POWERSWITCH!Removetheamplier’stop

cover and locate the plastic brackets, which

house the air ﬁlters. Push the two levers at the top

of these plastic brackets to access the foam

ﬁlters. Remove the foam air ﬁlters, clean them

thoroughly and then place them back into the

ampliﬁer. Secure the ﬁlter by snapping the plastic

brackets back into place.

TRANSFORMER THERMAL PROTECTION: If the

power transformer gets too hot, the thermal switch in-

side the transformer will trigger and will disconnect all

of the secondary power. When this occurs, there will

be no output signals coming from the ampliﬁer and

allLEDs,includingthePROTECTLED,willbeOFF.

Oncethetransformercoolsdown,powertotheampli-

ﬁer will automatically restore. In normal conditions,

the transformer will not overheat. Thermal protection

of the transformer indicates abnormal use, such as

excessiveoperationataverylowimpedanceathigh

signal levels. In this case, check and reconﬁgure your

loudspeakers connection. Reducing the output level

can also help.

NOTE: If the transformer overheats and

the thermal switch disconnects the power from

the ampliﬁer, it will take some time for the trans

former to cool down before power is restored. It

takes much longer for the transformer to cool

down compared to overheated heatsinks.

SHORT CIRCUIT: If the output is shorted because of

faulty wiring, the thermal circuitry will automatically

protect the ampliﬁer and mute the output signals. If

this occurs, the load will disconnect. Check and cor-

rect the short wire condition.

DC VOLTAGE PROTECTION: If an ampliﬁer chan-

nel detects a DC voltage at the loudspeaker output,

the protection circuitry will trigger and the ampliﬁer

will go into protection mode. In normal conditions

there should not be a signiﬁcant DC signal on the am-

pliﬁer outputs. DC on the outputs indicates a serious

problem with the ampliﬁer. In this instance, the ampli-

ﬁer must be referred to qualiﬁed service personnel.

SUBSONIC FREQUENCY PROTECTION: Built-in

high-pass subsonic ﬁlters provide subsonic frequency

protection for each channel. This protection prevents

subsonic audio signals, which may sometimes be

present in the music program, from reaching your

loudspeakers. Limiting the subsonic frequencies in

the output signal improves the sound reproduction by

reducingtheexcursionofthetransducer’sconeatlow

frequenciesandpreventsexcessiveheatinginsideof

the ampliﬁer.

NOTE: US-Series ampliﬁers also employ

switchable high-pass ﬁlters (HPF), which limit the

low frequency range to 50Hz when activated.

 TurntheseHPFsONwhenconnectingfullrange

speakers to the ampliﬁer. This will improve the

bass performance of most full range speakers by

 limitinguncontrolledandexcessiveconemotion

due to the lowest of frequencies. Using HPFs with

full range speakers provides more power to the

speaker’s rated range allowing higher SPLs. You

 maywanttoturnOFFtheHPFswhenusingthe

US-Series ampliﬁers with quality subwoofers.

CURRENT LIMITING PROTECTION: The output

stage of the ampliﬁer is protected by current-limiting

circuitry. This circuitry is inactive under normal condi-

tions. It activates only when it senses a dangerously

highcurrentthroughtheoutputtransistors,forexam-

ple when a connected load has an impedance that is

too low, or when the output of the ampliﬁer is shorted.

Current limiting protection engages only when it is

needed and is not indicated on the front panel. If

there is a constant over-current condition it will acti-

vatethethermalprotection.Inthiscase,thePROTECT

LEDonthefrontpanelwillilluminate.

CLIP LIMITERS: US-Series ampliﬁers have built-

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THE BEAUTY OF POWER

US SERIES AMPLIFIERS

in limiter circuitry for improved performance when

overloading.Thelimiteractivatesat“clipping”when

the output voltage reaches the power supply voltage

rails. Without limiters, the output voltage will grossly

distort if the signal elevates beyond this point. The

signalwaveformisattened(“clipped”),producing

excessivehighfrequencydistortionnotpresentinthe

originalsignal.Thismakesmusicsound“dirty”and

increases stress on the high frequency transducers,

signiﬁcantly shortening their life span (most loud-

speaker manufacturers will not honor warranties if

highfrequencydriversare“burnt”duetoaclipped

signal overload). Clip limiters effectively solve this

problem by compressing the signal at clipping. US-

Series ampliﬁers use intelligent clipping circuitry to

protect both the loudspeakers and ampliﬁer.

NOTE: US-1200 and US-1800 ampliﬁers have

a built-in limiter circuitry which is constantly

activated. The US-3000 and US-4000 ampliﬁers

 haveanexternalswitchlocatedontherear

panel, which activates and deactivates the clip

limiters. B-52 recommends the clip limiter switch

 onboththeUS-3000andUS-4000remainON.

 YoumaychoosetoturnOFFthelimiterswhen

using the US-3000 and US-4000 to power

subwoofers.

SETTING UP YOUR US-SERIES AMPLIFIER

CLIP LIMITER: Clipping is the result of an ampliﬁer running into a power supply limitation.

Themaximumoutputvoltagethatanyampliercanproduceislimitedbyitspowersupply.

Attemptingtooutputavoltagelevelthatexceedsthepowersupplyvoltagerailsresultsina

atteningeffectofthesignalcausingittoclip.Aclippedwaveformexhibitsseveredistor-

tions, making it sound harsh. The clip limiter detects this condition and reduces the gain to

minimize the amount of overdrive. To preserve as much of the program dynamics as possi-

ble,thelimiterreducestheaverageprogramleveluntilthepeaksbarelyclip.Eachchannel

hasitsowncliplimiterandyoucanswitchitONorOFF(onlyonUS-3000andUS-4000).

The clip limiter allows brief clipping which is not detectable to the ear. It activates when a

clip condition repeats, to avoid prolonged distortion. When driving full-range speakers, clip

limiting reduces the high frequency distortion caused by low frequency overload. It also

protectshigherfrequencydriversfromexcessoverdriveandharshclippingharmonics.

NOTE:YoumaywanttokeepthelimitersOFFwhenconnectingtheUS-3000and

US-4000 to power subwoofers.

HPF (High-Pass Filter): High Pass Filters (HPF) are also known as low-cut ﬁlters. HPFs

ontheUS-Seriesamplierscutoffsignalsbelow50Hz.Asaresult,bassreproductionis

optimized, since ultra-low frequencies, which most speakers cannot reproduce anyway, are

eliminated and more power becomes available for the reproduction of the remainder of the

music signal.

NOTE: You should set the ﬁlters to best suit the frequency response of your speakers as

somespeakersareparticularlysensitivetoover-excursion.The50HzltersontheUS-Series

ampliﬁers work well with most full-range speakers.

NOTE: FormostsubwoofersandinstudioapplicationskeeptheHPFintheOFFposition.

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MODE SELECT:

STEREO MODE

InSTEREOmode,bothchannelsoperateindependently,withtheirrespectiveinputgain

controls. Signal at the Channel 1 input produces output at Channel 1, while the signal

at Channel 2 input produces output at Channel 2. The minimum load impedance for

STEREOoperationis2Ohmsperchannel.

PARALLEL MODE

WhensettoPARALLELmode,asignalappliedtoChannel1’sinputwillbeamplied

and appear at both of the Channel 1 and 2 outputs. The level control knobs will oper-

ateontheirrespectivechannels.Channel2’sinputisinactiveinthePARALLELmode.

ThePARALLELmodeiswell-suitedforapplicationswhenyouneedtofeedtwospeakers

withthesamesignalbuteachspeakerispoweredbyitsownamplierchannel.Mini-

mumloadimpedanceforPARALLELoperationis2Ohmsperchannel.

BRIDGED MONO MODE

Bridged mono mode combines both ampliﬁer channels to make a powerful single-chan-

nelamplier.Onechannel”pushes”andtheotherchannel“pulls”thesignalequally,

doubling the voltage. When the voltage is doubled, the power is quadrupled if the

same impedance load is used.

 InaBRIDGEmode,thesignalmustbeappliedtoChannel1’sinputonlyand

Channel 1’s gain control is used to adjust the signal level. The gain control of Channel

2isnotusedandinput2isinactiveinBRIDGEmode.

NOTE:MinimumloadimpedanceinBRIDGEmodeis4Ohms.Connectinga

 lowerimpedanceloadtotheamplierintheBRIDGEmodemaytriggerthe

protection circuitry. In some instances it may cause severe damage to the ampliﬁer,

which is not covered by the warranty.

WARNING: MAKESURETHEIMPEDANCEOFTHESPEAKERSCONNECTEDIN

 ABRIDGEMODEARENOTLOWERTHANSPECIFIED!!!

WARNING: Do not connect two 4 ohms subwoofers in parallel in BRIDGE mode,

as the total impedance halves in such a parallel connection. The total impedance

will be 2 ohms, and will cause constant overheating and distortion of ampliﬁer. It

 willalsocauseconstanttriggeringoftheACcircuitbreakerandcoulddamage

your ampliﬁer.

NOTE:IntheBRIDGEmodeaspeakerisconnectedtobothofthechannels’

outputs and is not connected to the ground of the ampliﬁer on both ends.

 DONOTATTEMPTTOGROUNDYOURSPEAKER!

B-52 US Series Professional Power Amplifiers - Instruction Manual

THE BEAUTY OF POWER

US SERIES AMPLIFIERS

CONNECTING YOUR SPEAKERS

Stereo Mode

Parallel Mode

Bridged Mono

5-Way Output Binding Posts

Bridged / Mono

5-Way Output Binding Posts

THE BEAUTY OF POWER

B-52 US Series Professional Power Amplifiers - Instruction Manual

US SERIES AMPLIFIERS

Stereo Mode

Parallel Mode

Bridged Mono

SPK+ to PIN 1+

SPK- to PIN 1-

SPK+ to PIN 1+

SPK- to PIN 1-

SPK+ to PIN 2+

SPK- to PIN 2-

SPK+ to PIN 1+

SPK- to PIN 1-

SPK+ to PIN 1+

SPK- to PIN 1-

SPK+ to PIN 1+

SPK- to PIN 1-

SPK+ to PIN 2+

SPK- to PIN 2-

SPK+ to PIN 1+

SPK- to PIN 1-

Bridged / Mono

SPK+ to PIN 1+

SPK- to PIN 2+

B-52 US Series Professional Power Amplifiers - Instruction Manual

THE BEAUTY OF POWER

US SERIES AMPLIFIERS

WIRING

There are multiple ways to connect a US-Series ampli-

ﬁer to other audio equipment. The US-Series features

balanced inputs and link outputs, which allows you to

connect both balanced and unbalanced signals.

For speaker connections, you can use either binding

postsorSpeakon™connectors.

NOTE: Use speaker wires with the lowest

gauge available. The thicker the speaker wires

are, the less output signal you will lose.

UNBALANCED 1/4” CONNECTOR

BALANCED 1/4” CONNECTOR

SPEAKON

OUTPUT CONNECTOR

NOTE: For connections of unbalanced sources

viabalancedcables/plugs,theringand

sleeve have to be bridged at the TRS plug.

THE BEAUTY OF POWER

B-52 US Series Professional Power Amplifiers - Instruction Manual

US SERIES AMPLIFIERS

US-1200 US-1800 US-3000 US-4000

Rated Output Power STEREO BOTH CHANNELS DRIVEN @ 1KHZ, 1%THD

8 Ohms 210 watts 300 watts 500 watts 700 watts

4 Ohms 330 watts 475 watts 800 watts 1100 watts

2 Ohms 430 watts 700 watts 1200 watts 1600 watts

Rated Output Power BRIDGED MONO @ 1KHZ, 1%THD

8 Ohms 650 watts 950 watts 1600 watts 2200 watts

4 Ohms 850 watts 1400 watts 2400 watts 3200 watts

Input Sensitivity 1.23 Vrms (+4 dBu) for full power @ 4 Ohms

Input Impedance 30K ohms Balanced/15K ohms Unbalanced

Frequency Response 0/-0.5dB: 20Hz - 20kHz; 0/-3dB: 5Hz - 60kHz

Signal to Noise Ratio Better than 100dB (20Hz - 20kHz)

Distortion (SMPTE-IM) Less than 0.03%

Output Circuitry AB AB H H

Cooling Continuosly variable speed fan, front to rear

Protection Short circuit, thermal, current limit, DC offset, AC current inrush,

RF protection, subsonic, turn on/off muting

Connectors Input: Combo female XLR & 1/4” TRS jack. Link: Male XLR

Output: Both 5-way biding post and Speakon

Controls Front: Power on/off switch, volume controls for each channel

Rear: Mode switch (stereo / parallel / bridge), HPF on/off,

Limiter on/off (US3000/4000)

Indicator

Power, parallel, bridge. Each channel: Signal, -20dB, -10dB, clip, protect

Power Requirements 115/230V 60/50Hz factory conﬁgured

AC current consumption Both channels driven at 4 Ohm load, at 115Vac (for 230V divide by 2)

Typical level, 4.5A 6.3A 7A 9.6A

1/8 power pink noise

Severe level, 7A 9.6A 14.8A 19.8A

1/3 power pink noise

Dimensions (W x H x D) 19” (482mm) x 3.5” (88mm) x 17.2” (438mm)

Net Weight 28lb (13kg) 35lb (16kg) 43lb (19kg) 49lb (22.3kg)

SPECIFICATIONS

* Speciﬁcations are subject to change without notice.

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U.S. Amps US-1800 User manual

Brand: U.S. Amps

Model: US-1800

Category: Supplementary music equipment

Type: User manual

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U.S. Amps US-1800 User manual

U.S. Amps US-1800 User manual

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